MPI Magnetic Peripheral Incorporated
MPI from Minneapolis MN was created originally as a joint venture of Control Data Corporation and Honeywell where Honeywell brought to CDC the contribution of its disk business represented by its ex-GE plant of Oklahoma City. CII-Honeywell Bull soon after brought to MPI its ex-Honeywell plant of Heppenheim, Germany that gave 10% shares of MPI.
MPI regrouped the whole disc business of Control Data and had as customers Honeywell, CII-HB and Control Data for their proprietary systems and other companies as OEM suppliers and CDC as a supplier for end-user selling on the IBM compatible market (IBM, Amdahl, ...)
When MPI was formed, its main production was 3330-like third generation of disc subsystems. In the following years, they announced and delivered no more than one year after IBM, compatible discs such as Winchester 3340, fixed 3350 and 3370. Those drives were delivered with IBM interfaces or with specific interfaces. Honeywell and CII-HB for their Level 66 and 64 line shad specified DLI device level interface, a proprietary standard. So, MPI produced 3330 and 3350 to that standard.
Subsequently, the growing minicomputer market caused MPI to manufacture cheaper non-removable disks that Honeywell used on Level 6 and Level 62 market. The interface was a proprietary variant of the standard SMD interface.
In the 1980s, several important Honeywell customers, starting by GE Information Systems, started to request the connection of IBM compatible discs subsystems and pressed for giving up proprietary interfaces. Honeywell negotiated with IBM Storage Division the direct supply by IBM of San Jose's produced discs and with IBM Poughkeepsie a joint effort to adapt DPS-90 interfaces to new IBM fiber channels. MPI was still the supplier of smaller discs for small DPS-8000. Bull, on its side, choose Hitachi 8-inches discs for the DPS-7000.
Honeywell, followed by Bull, relinquish to CDC their shares into MPI. The disc market became in 1985 more and more oriented to the minicomputer and the PC, with the creation of Shugart Associates and the standardization of the SCSI interface (a derivative of Shugart SASI). Once a prime actor of the market, CDC saw its market share starting to melt and decided to transfer its disc activities to its competitor Seagate.